Method and a machine for manufacturing filters for tobacco products

ABSTRACT

Filters for cigarettes are manufactured on a machine by which a web of activated carbon fiber fabric is decoiled from a roll, fed into a fragmentation device and broken up into filaments or particles. The fragments are gathered by a first unit into a continuous flow directed up and through the top outlet of an ascent channel into a further unit with a slidable and air-permeable aspirating belt such as will attract and retain the filaments or particles rising through the channel and shape them progressively into a continuous stream which is then released by the belt to the infeed of a unit equipped with a garniture section along which a strip of paper is wrapped around the continuous stream to form a continuous filter rod. Finally, the rod is fed through a rotary cutter and divided into sticks that will provide the single filter plugs for attachment to cigarettes.

BACKGROUND OF THE INVENTION

The present invention relates to a method and to a machine formanufacturing filters applicable to tobacco products, in particularcigarettes.

The prior art embraces the practice of attaching filters to cigaretteswith tipping papers. Such filters are manufactured by a process in whicha flow of filter material, usually cellulose acetate drawn from a supplysuch as a bale, is extended, stretched and treated with additives, inparticular plasticizers. The flow is processed in such a way as toobtain a continuous stream of filter material and the stream thenenveloped in a paper plugwrap to fashion a continuous filter rod, whichwill be divided ultimately into single filter plugs.

Also embraced by the prior art are filters for cigarettes utilizingactivated carbon granules as the filter material. In effect, activatedcarbon is an excellent filtration medium, that is to say with a highcapacity for absorbing nicotine, tar and other harmful productscontained in smoke.

Owing to the relatively large particle size of the granules, however,filters of this type do not present a sufficiently compact structure.

In effect, the interstitial spaces between the granules offer a path ofleast resistance to the smoke, thus significantly reducing the capacityof such filters to trap impurities.

A further drawback consists in the fact that the equipment employed inmanufacturing such filters is relatively complex, not least in view ofthe need to place the granular filters in question between two celluloseacetate filter plugs produced by the method outlined briefly above,which function not only as filters but also as a means of preventing theendmost granules of the activated carbon filter element from escapingduring the various processing steps.

The object of the present invention is to provide filters affording ahigh absorption capacity and guaranteed devoid of the drawbacksmentioned above.

A further object of the invention is to provide a method and a systemfor the manufacture of such filters that will be unaffected by thedrawbacks of conventional equipment as mentioned above, while affordingsimplicity and ease of implementation.

SUMMARY OF THE INVENTION

The stated objects are realized according to the present invention in amethod of manufacturing filters for tobacco products, which comprisesthe steps of feeding a continuous stream of filaments or particlesconsisting in activated carbon fibers to the infeed of a unit by which acontinuous filter rod is formed, enveloping the continuous stream in astrip of wrapping material to form the continuous filter rod, andfeeding the continuous rod to a cutter device by which it is dividedinto discrete filter sticks.

The stated objects are realized similarly in a filter maker embodiedaccording to the invention, comprising a reservoir that serves tocollect and to contain a mass of filaments or particles of activatedcarbon fibers, also feed means supplying the reservoir, a unit by whichthe activated carbon filaments or particles are formed into at least onecontinuous stream, a unit by which the continuous stream is formed intoa continuous filter rod, and cutter means by which the continuous rod isdivided into discrete filter sticks.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in detail, by way of example, withthe aid of the accompanying drawings, in which:

FIG. 1 illustrates a portion of a machine for making filters applicableto tobacco products, embodied in accordance with the present invention,viewed schematically and in perspective and cut away in part;

FIG. 2 illustrates the machine of FIG. 1 with certain parts omitted andothers added, viewed in elevation and on a different scale;

FIG. 3 illustrates the machine of FIG. 1 in a second embodiment, viewedschematically and in perspective, and cut away in part;

FIG. 4 illustrates a variation in embodiment of the portion of themachine in FIG. 3, viewed schematically and in perspective;

FIG. 5 illustrates the machine according to the present invention in athird embodiment, viewed in elevation;

FIG. 6 illustrates a cigarette, in perspective, furnished with a filtermanufactured by the method and employing a machine according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2 of the accompanying drawings, 1 denotes afilter making machine, in its entirety. Such a machine 1 comprises areservoir 2 containing a mass 3 of filaments or particles of activatedcarbon fibers, also a unit 4 by which the filaments or particles of themass 3 are formed into a continuous flow 5, and a unit 6 by which thecontinuous flow 5 is formed into two continuous streams 7 of filamentsor particles of activated carbon fibers.

In addition, and as illustrated in FIG. 2, the machine 1 comprises aforming unit 8 on which two continuous filter rods 9 are assembled bywrapping each of the aforementioned continuous streams 7 of fibers in arespective strip 10 of paper decoiled by a relative feed device 11 froma corresponding roll 12.

The continuous filter rods 9 advance along a path denoted P to theoutfeed end of the forming unit 8, where they are divided into discretesticks 13 by a cutter device 14.

Whilst the example described and illustrated relates to a machine withtwo processing lines, hence able to assemble two continuous filter rodssimultaneously from respective streams of fibers, it will be appreciatedthat the disclosure applies equally to a machine with just oneprocessing line.

15 denotes a continuous web of fabric made from activated carbon fibers.More particularly, the material in question is obtained by a process ofcalcination in the absence of air or oxygen, known as carbonization,followed by an activating step consisting in oxidation at hightemperature. The resulting fibers can be prepared for use, as in thecase considered here, in the form of fabric.

Also indicated in FIG. 1 are decoil and guide means denoted 16, in theirentirety, constituting means by which to feed the web 15 of fabric alonga predetermined path denoted P1. Such means comprise a device 17 servingto decoil a bulk roll 18 of the fabric 15 rotatable about a horizontalaxis 18 a, also a roller 19 by which the fabric 15 is diverted onto asubstantially vertical leg of the path P1 toward a fragmentation device20 positioned above the reservoir 2 and illustrated schematically as apair of rollers 21 and 22 contrarotating about axes parallel to theaforementioned horizontal axis 18 a.

The fragmentation device 20 serves to break up the fabric 15, forexample utilizing teeth or tines presented by the rollers 21 and 22, andreduce it to filaments or particles having the consistency of fluff,accumulating to create the aforementioned mass 3 internally of thereservoir 2.

The unit 4 serving to form the continuous flow 5 of filaments orparticles is housed in a vertically oriented enclosure denoted 23,delimited laterally by two vertical walls 24 and 25, and uppermost by ahorizontal wall 26 presenting an opening 27 to the reservoir 2 throughwhich the mass 3 of fluff can drop onto a power-driven toothed roller28.

The mass 3 of fluff is directed by the roller 28 downwards and into alower chamber 29 delimited at the bottom by a conveyor belt 30 whichcarries the fluff toward a carding device 31 equipped with a cardingroller 32 rotatable about an axis 32 a lying transversely to thevertical side walls 24 and 25 and operating in conjunction with aproportioning roller 33.

With the arrangement thus described, the mass 3 of fluff consisting infilaments or particles of activated carbon fibers is directed by thetoothed roller 28 onto the belt 30, and by the belt toward the cardingroller 32, from which a layer of fluff substantially equal in thicknessto the radial dimension of the carding teeth is transferred away fromthe chamber 29 and beyond the position of the selfsame roller 32tangential to the proportioning roller 33.

It will be seen that the toothed roller 28 and the belt 30 constitutefirst conveyor means serving to supply the carding device 31 with flufffrom the reservoir 2.

The layer of filaments or particles of activated carbon fiber is takenup by an impeller roller 34 rotatable about an axis parallel to the axis32 a of the carding roller, and projected into a descent channel 35.

The descent channel 35 extends in a substantially vertical direction andis disposed with the bottom end facing the periphery of a toothedtake-up unit denoted 36, comprising a first and a second toothed rollercombining one with another to transfer the layer of filaments orparticles of activated carbon fibers onto a transfer belt 37.

The transfer belt 37 runs from right to left, as viewed in FIG. 1, andis angled upward with the runout end located beneath the inlet of anascent channel 38 internally of which a continuous flow 5 of thefilaments or particles of activated carbon fibers is entrained in anascending air current generated by pneumatic means of conventional type(not illustrated).

Accordingly, the descent channel 35, the toothed take-up unit 36 and thetransfer belt 37 combine to establish second conveyor means interposedbetween the carding device 31 and the ascent channel 38.

The top outlet end 39 of the ascent channel is enclosed by a pair ofaspirating belts 40 made of air-permeable material and constituting apart of the unit 6 by which the aforementioned continuous streams 7 areformed. The two belts 40 are looped around two return pulleys 41 drivenin rotation about respective horizontal axes. Compassed within the loopcreated by the belts 40 is a chamber 42 connected to a source ofnegative pressure (not illustrated) and delimited on the underside by awall 43 pierced with suction holes 44.

Thus, filaments or particles of activated carbon fibers making up thecontinuous flow 5 are directed up through the ascent channel 38 and intocontact with the bottom branches of the aspirating belts 40 as theseslide against the aforementioned wall 43, whereupon the fibers cling tothe belts and gather progressively to form the aforementioned continuousstreams 7, which are conveyed to the infeed 45 of the unit 8 that willform them into continuous filter rods 9.

More precisely, and referring to FIG. 2, the continuous streams 7 ofmaterial are released onto respective strips 10 of paper supported bythe top branches of respective looped conveyor belts 46, of which oneonly is visible in FIG. 2, forming part of the aforementioned feeddevice 11 and fashioned from a textile material.

The forming unit 8 further comprises a beam 47, extending along theaforementioned path P, by which the paper strips 40 are constrained towrap around the respective continuous streams 7 of filaments orparticles of activated carbon fibers, thus bringing about the assemblyof the two filter rods 9. As the assembled components advance along thebeam 47, one longitudinal edge of each strip 10 will be gummed byapplicator means (not illustrated) and stuck, so as to stabilize thewrap around the two rods 9.

FIG. 3 illustrates an embodiment of the machine differing from that ofFIG. 1 inasmuch as the reservoir 2 is placed at the outlet of a duct 48of which the inlet is connected to a fragmentation device shownschematically as a block denoted 20. Also, the unit 4 forming thecontinuous flow 5 of filaments or particles of activated carbon fibersis simplified in this embodiment, comprising only the toothed take-upunit 36, placed at the bottom outlet end of the reservoir 2 in thisinstance, the transfer belt 37, and the ascent channel 38.

It will be seen that the decoiling and guiding means 16 serving todirect a web 15 of fabric along a predetermined path P1 in the exampleof FIG. 1, and the duct 48 in FIG. 2, are designed to act as feed meansserving the reservoir 2.

FIG. 4 illustrates an embodiment of the machine differing from that ofFIG. 1 inasmuch as the reservoir 2 is fed by a conveyor belt 49 angleddownward and toward the inlet of the reservoir 2, onto which the mass 3of filaments or particles of activated carbon fibers is released fromabove. More exactly, the top infeed end of the belt 49 is positionedbeneath the fragmentation device 20 by which the web 15 of activatedcarbon fiber fabric will be broken up.

In like manner to the example of FIG. 3, the unit 4 serving to form thecontinuous flow 5 of filaments or particles of activated carbon fibersis simplified in this embodiment, consisting only in the toothed take-upunit 36, positioned at the bottom outlet end of the reservoir 2, thetransfer belt 37 and the ascent channel 38.

Referring to the example illustrated in FIG. 5, the block denoted 50represents a spinning unit such as will produce a plurality of strands51 consisting in filaments or particles of activated carbon fibers,obtainable from the web 15 of fabric or from a mass 3 of fluffcontaining filaments or particles of activated carbon fibers, or unwoundfrom respective reels. The strands 51 emerging from the spinning unit 50are fed into a forming unit shown as a block denoted 52, and gathered bythis same unit into a continuous stream 7 of filaments or particles ofactivated carbon fibers.

Alternatively, the stream 7 could consist in a rope or braid ofactivated carbon filaments or particles unwound from a respective reel.

In a further embodiment of the machine 1, not illustrated in thedrawings, the stream 7 could be processed directly by the forming unit52 from a layer of fluff.

Proceeding downstream of the forming unit 52, the unit 8 by which thefilter rods 9 are assembled is no different to that described withreference to the example of FIG. 2.

Finally, FIG. 6 illustrates a cigarette 53 with a filter 54 obtainedfrom a stick 13 manufactured on the machine 1 by the methods describedabove. In particular, the filter 54 in question presents a much highercapacity for absorbing impurities than traditional filters made withcellulose acetate or activated carbon granules.

In effect, the microporosity of the filter in question is such as tomake it especially suitable for trapping pollutants of low molecularweight. The filter described and illustrated might also be utilized inconjunction with traditional cellulose filters to assemble compositefilters.

Furthermore, and in the light of the foregoing, a filter 54 obtained inthis manner is considerably simpler to manufacture than a conventionalfilter.

1. A method of manufacturing filters for tobacco products, comprises thesteps of: feeding a continuous stream of filaments or particlesconsisting in activated carbon fibers to the infeed of a unit by which acontinuous filter rod is formed; enveloping the continuous stream in astrip of wrapping material to form the continuous filter rod; andfeeding the continuous rod toward a cutter device by which it is dividedinto discrete filter sticks. 2) A method as in claim 1, furthercomprising the steps of collecting a mass of filaments or particlesconsisting in activated carbon fibers internally of a reservoir,transforming the mass into a continuous flow of such filaments orparticles, and directing the continuous flow toward a unit by which thefilaments or particles consisting in activated carbon fibers are formedinto the continuous stream. 3) A method as in claim 1, comprising thesteps of feeding a web of fabric composed of activated carbon fibersalong a predetermined path, subjecting the web of fabric to the actionof a fragmentation device by which it is broken up into filaments orparticles, forming the filaments or particles into a continuous flow,and directing the continuous flow into a unit by which it is gatheredinto the continuous stream of filaments or particles consisting inactivated carbon fibers. 4) A method as in claim 3 comprising a step,included between the fragmentation step and the step of forming thefilaments or particles of activated carbon fibers into a continuousflow, of collecting the mass of filaments or particles consisting inactivated carbon fibers internally of a reservoir. 5) A method as inclaim 1, wherein the continuous stream of filaments or particlesconsisting in activated carbon fibers is obtained, beginning with aplurality of strands, through a step of feeding the strands into meansby which they are formed into the continuous stream of filaments orparticles consisting in activated carbon fibers. 6) A method as in claim1, wherein the continuous stream of filaments or particles consisting inactivated carbon fibers is obtained, beginning with a layer of filamentsor particles consisting in activated carbon fibers, through a step offeeding the layer into means by which it is formed into the continuousstream. 7) A method as in claim 1, wherein the continuous streamconsists in a rope or braid unwound from respective reel. 8) A machinefor manufacturing filters for tobacco products, comprising: a reservoirinternally of which to collect and to contain a mass of filaments orparticles of activated carbon fibers; feed means supplying thereservoir; a unit by which the filaments or particles of activatedcarbon fibers are formed into at least one continuous stream; a unit bywhich the continuous stream is formed into a continuous filter rod; andcutter means by which the continuous rod is divided into discrete filtersticks. 9) A machine as in claim 8, wherein the feed means comprisemeans by which to decoil and guide a web of fabric composed of activatedcarbon fibers from a relative roll, and a fragmentation device by whichthe web is broken up into filaments or particles of activated carbonfibers. 10) A machine as in claim 8, comprising a unit by whichfilaments or particles of activated carbon fibers are formed into acontinuous flow, interposed between the reservoir and the unit by whichthe filaments or particles of activated carbon fibers are formed into acontinuous stream. 11) A machine as in claim 10, wherein the unit bywhich filaments or particles of activated carbon fibers are formed intoa continuous flow comprises a carding device, first conveyor meansfeeding the carding device from the reservoir, an ascent channel inwhich the filaments or particles of activated carbon fibers are formedinto a continuous flow and from which the flow is fed to the unitforming the continuous stream, and second conveyor means interposedbetween the carding device and the ascent channel. 12) A machine as inclaim 10, wherein the unit by which filaments or particles of activatedcarbon fibers are formed into a continuous flow comprises an ascentchannel inside which the filaments or particles of activated carbonfibers are formed into a continuous flow and from which the flow is fedto the unit forming the continuous stream of filaments or particles ofactivated carbon fibers, and second conveyor means interposed betweenthe reservoir and the ascent channel. 13) A machine as in claim 8,wherein the unit by which filaments or particles of activated carbonfibers are formed into at least one continuous stream comprises anaspirating conveyor belt looped around return pulleys and positioned atthe top outlet end of the ascent channel supplying the unit by which thecontinuous stream of filaments or particles of activated carbon fibersis formed into continuous filter rod together with a strip of wrappingmaterial designed to envelop the selfsame continuous stream of filamentsor particles of activated carbon fibers. 14) A machine as in claim 8,comprising means, interposed between the reservoir in which to collectand contain a mass of filaments or particles of activated carbon fibersand the unit by which the continuous filter rod is formed, such as willform the continuous stream of filaments or particles of activated carbonfibers directly from the mass of filaments or particles of activatedcarbon fibers. 15) A machine as in claim 8, comprising a spinning unit,interposed between the reservoir in which to collect and contain a massof filaments or particles of activated carbon fibers and the unit bywhich the continuous filter rod is formed, such as will produce aplurality of strands consisting in filaments or particles of activatedcarbon fibers, and means by which to form the continuous stream offilaments or particles of activated carbon fibers from the selfsamestrands. 16) A machine as in claim 13, wherein the unit by which thecontinuous filter rod is formed with the strip of wrapping materialcomprises a beam along which the strip of wrapping material is closedaround the continuous stream of filaments or particles of activatedcarbon fibers. 17) A filter for tobacco products, characterized in thatit is composed at least in part of filaments or particles consisting inactivated carbon fibers prepared by the method as in claim
 1. 18) Amachine as in claim 9, comprising a unit by which filaments or particlesof activated carbon fibers are formed into a continuous flow, interposedbetween the reservoir and the unit by which the filaments or particlesof activated carbon fibers are formed into a continuous stream. 19) Amachine as in claim 9, wherein the unit by which filaments or particlesof activated carbon fibers are formed into at least one continuousstream comprises an aspirating conveyor belt looped around returnpulleys and positioned at the top outlet end of the ascent channelsupplying the unit by which the continuous stream of filaments orparticles of activated carbon fibers is formed into continuous filterrod together with a strip of wrapping material designed to envelop theselfsame continuous stream of filaments or particles of activated carbonfibers. 20) A machine as in claim 10, wherein the unit by whichfilaments or particles of activated carbon fibers are formed into atleast one continuous stream comprises an aspirating conveyor belt loopedaround return pulleys and positioned at the top outlet end of the ascentchannel supplying the unit by which the continuous stream of filamentsor particles of activated carbon fibers is formed into continuous filterrod together with a strip of wrapping material designed to envelop theselfsame continuous stream of filaments or particles of activated carbonfibers.